The Doppelgänger is a powerful tool in the arsenal of the GM. It's a guaranteed way to
sow confusion and paranoia amongst your players. And the great thing is that once they've been exposed to it,
you don't actually have to use it again. Just say things like, "Fred seems to be behaving
a bit strangely lately," every now and then.

If you've done your job right, this will be enough to incite intra-party conflict and hopefully
combat. And all with none of the PCs ever having done anything wrong.

In the real world of the Terminators & Temporal Paradoxes universe, of course, the Terminator movies don't exist.
That's the premise of this entire comic, after all. But most of the other things we know and love (such as history-changing time travellers)
do, albeit modified by the lack of Terminator:

Without the success of Terminator to spark interest in robotics, Lost in Space was never revived
with a movie and a new series, and remains an obscure short-running TV show.

I, Robot was never made into a film. Asimov fans never had it so good.

The major cybernetic world background that pervades all of Western culture is Blade Runner, despite it never being much good.
The original film was remade recently into a new, updated television series with a bigger budget, high-tech computerised special effects, and edgy writing.
And it sucked.

Throughout the 1980s and 90s, all the greatest Hollywood blockbusters were big-budget biblical epics.

Vision-Impaired Transcript

GM: John you make your way across the steelworks, towards the sound of your mother's voice.Sarah: John, help me!GM: A second Sarah steps out, pointing a gun at the first Sarah!Second Sarah: Out of the way, John.Sarah: I spin and drop the other Sarah with a flying kick!GM: Uh, Jim, you're that Sarah, not this one.Sarah: {transmuting into the T-1000} Yeah, silly! This one's me! Yay!Second Sarah: {actually the real Sarah} I blow the Terminator away! Sorry, Sally.[SFX]: K-boom!T-1000: It's okay! You can't hurt me!GM: She's right. Plus, you're out of ammo.Sarah: Uh-oh.Dyson: {flashback to the scene at the Cyberdyne Systems building} You wouldn't be in this mess if you hadn't abandoned me back at Cyberdyne.GM: Oh come on Pete, that's what you get for taking Dependent Children and Fate (Responsible for Downfall of Civilisation) just to get a few more skill points in Electronic Engineering!GM: Annie, The machinery pulls your shattered body up to where you can see the others.Terminator: Hasta la vista, baby.GM: Is that the best line you can think of?